Error sources on the land surface temperature
retrieved from thermal
infrared single channel remote sensing data
J. C. JIME´ NEZ-MUN˜ OZ
and
J. A. SOBRINO
Global Change Unit, Department of Thermodynamics, Faculty of Physics, University of Valencia, Dr. Moliner 50, 46100, Burjassot, Spain
International Journal of Remote Sensing, Vol. 27, No. 5, 10 March 2006, 999–1014
In this paper, a theoretical study complementary to others given in the literature about the errors committed on the land surface temperature retrieved from the radiative transfer equation in the thermal infrared region by remote sensing techniques has been analysed. For this purpose, the MODTRAN 3.5 code has been used in order to simulate different conditions and evaluate the influence of several parameters on the land surface temperature accuracy: atmospheric correction, noise of the sensor, land surface emissivity, aerosols and other gaseous absorbers, angular effects, wavelength uncertainty, full-width halfmaximum of the sensor and band-pass effects. The results show that the most important error source is due to atmospheric effects, which leads to an error on surface temperature between 0.2 K and 0.7 K, and land surface emissivity uncertainty, which leads to an error on surface temperature between 0.2 and 0.4 K. Hence, assuming typical uncertainties for remote sensing measurements, a total error for land surface temperature between 0.3 K and 0.8 K has been found, so it is difficult to achieve an accuracy lower than these values unless more accurate in situ values for emissivity and atmospheric parameters are available.
8. Conclusions
The LST retrieved by thermal infrared remote sensing techniques is one of the most used parameters for environmental studies. For this purpose, several algorithms can be used, as split-window or dual-channel, dual-angle, etc. These algorithms retrieve LST with a certain error, so they are obtained by an approximation to the radiative transfer equation, simulation procedures and statistical fits. However, the use of the radiative transfer equation itself does not guarantee an accurate value of LST, even if the atmospheric correction is free of errors. Only the uncertainty on the land surface emissivity leads to an error on the LST of 0.4 K, although this error is reduced to 0.2 K when in situ values are considered. The atmospheric correction introduces errors on the LST retrieval of 0.2 K or 0.7 K depending if in situ or remote sensing data are used, respectively. So, in optimal conditions and when in situ data are available, a minimum error of 0.3 K is obtained, whereas when remote sensing data are considered a minimum error of 0.8 K is expected. When other error sources such as noise error, bandpass effects and wavelength indetermination are considered, then an accuracy for the LST retrieval between 0.5 and 0.9 K is obtained.
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